Community prevalence of hepatitis B infection and modes of transmission in Tamil Nadu, India.

BACKGROUND AND OBJECTIVE: There have been very few community based studies on prevalence of hepatitis B virus (HBV) infection in India. We undertook this study to determine the prevalence of HBV infection in a southern State of India, Tamil Nadu and to describe the important factors related to transmission of the virus in the community. METHODS: Analysis of stored blood samples from a representative population of Tamil Nadu from an earlier community cluster survey on sexually transmitted diseases (STD) prevalence using proportionate to population size (PPS) technique was done. Serum markers of HBV viz., hapatitis B surface antigen (HBsAg), hepatitis B e antigen (HBe Ag) and antibody to surface antigen (anti-HBs) were performed. RESULTS: 1981 subjects were screened in the study. HBsAg prevalence was 5.7 per cent (CI 4.6- 6.8) with 23.5 per cent (25/106) of these having positive HBe-antigen. Community seroprevalence (HbsAg + anti-HBs) of hepatitis B infection was 27.4 per cent (CI: 25.3-29.5) with the highest prevalence of 32.7 per cent (CI: 30.2-35.2) noted in the 15-20 yr age group. Significant independent association (OR 1.4; P=0.006) was detected with family history of exposure to HBV infection by logistic modeling. Other risk factors noted to have significant association were use of disposable needles during injection (OR 0.5; P=0.02) in men, smoking (OR 3; P=0.04) and use of condom (OR 0.6; P=0.08) in women. INTERPRETATION AND CONCLUSION: This community based study shows a high prevalence of hepatitis B infection in the state of Tamil Nadu with the highest prevalence being in the younger (15-20 yr) age group. High prevalence rate in childhood with e-antigenemia seen in 23.5 per cent of HBsAg positive subjects suggest childhood transmission. Poor injection practices and high-risk sexual behavior were found to be additional risk factors for transmission of the disease in the community.

Imaging patients with "post-cholecystectomy syndrome": an algorithmic approach.

AIM: To assess the role of ultrasound (US), magnetic resonance cholangiopancreatography (MRCP) and liver function tests (LFTs) in the evaluation of selected patients presenting with late post-cholecystectomy syndrome (PCS) who were referred for endoscopic retrograde cholangiopancreatography (ERCP). MATERIALS AND METHODS: In a retrospective study a final group of 42 patients with PCS referred for diagnostic ERCP underwent MRCP and abdominal US. ERCP and MRCP images were assessed for bile duct diameters and the presence of strictures and stones. A common bile duct (CBD) diameter of < 10mm was considered normal, whereas > or = 10mm was considered abnormal on US. Findings were correlated to LFTs with contingency table results performed for single techniques and combination of methods. RESULTS: In total 14 stones and one stricture were seen. US had a high negative predictive value (86.4%). MRCP had a sensitivity of 100% and specificity of 88.0%. ERCP is the most accurate test but failed in 11 patients, five of whom had a stone. The accuracy of US and LFTs increases to 93.8% if test results agree in either negative or positive outcome. CONCLUSION: US and LFTs are first-line tests in PCS. If the CBD on US is > or = 10mm, but no cause is identified, MRCP should be performed. If US and LFTs are normal then MRCP is not necessary. The availability of LFTs raises the diagnostic value of imaging.

Ultrasound-guided endocavitary drainage of pelvic abscesses: technique, results and complications.

AIM: To evaluate the experience in our institution with ultrasound-guided transrectal and transvaginal (endocavitary) drainage of pelvic abscesses. MATERIALS AND METHODS: Eighteen patients (four male, 14 female; mean age 55 years, range 30-78 years) presenting with pelvic abscesses were referred to our institution for therapeutic drainage over a 4 year period. Patients received broad-spectrum antibiotics prior to drainage, which was performed by either the transvaginal or transrectal route under ultrasound guidance. Patients were given sedo-analgesia in the form of midazolam and fentanyl and local anaesthesia was also employed. Eight French catheters were inserted into the abscess cavities, and patients were subsequently monitored on a daily basis by a member of the interventional radiology team until such time as it was deemed appropriate to remove the catheter. RESULTS: Eighteen catheters were placed in 17 patients, and transvaginal aspiration alone was performed in one patient. Drainage was successful in 16 of 17 patients, but a transgluteal approach was ultimately required in the remaining patient to enable passage of a larger catheter into an infected haematoma. The mean duration of drainage was 5 days, mean time to defervesce 2 days. Spontaneous catheter dislodgement occurred in four patients associated with straining, but this did not have any adverse effect in three of the four patients. CONCLUSION: Endocavitary drainage is an effective method of treatment for pelvic abscesses. Spontaneous catheter dislodgement does not affect patient outcome.

Displacement of occluded plastic endoprostheses into the duodenum during percutaneous biliary drainage: description of an under-reported technique.

AIM: Percutaneous transhepatic biliary drainage (PTBD) is occasionally requested in patients with an occluded plastic stent in situ. We describe a technique for dislodging the stent into the duodenum during PTBD. MATERIALS AND METHODS: Twelve patients (M:F, 9:3 mean age 70 years) with plastic stents in the common bile duct (CBD) underwent PTBD. Eleven patients had malignant obstruction and one patient had Mirizzi's syndrome and a large duodenal diverticulum. PTBD was performed using right lobe access in nine patients and a left hepatic access in three patients. The level of biliary obstruction was at the lower CBD in five patients, mid-CBD in four patients and upper CBD in three patients. After standard percutaneous biliary access was established, an 8mm by 4 cm balloon catheter was gently inflated alongside the upper end of the plastic stent and advanced over a stiff guidewire, towards the duodenum, to dislodge the plastic stent. RESULTS: Plastic stents were successfully dislodged in all 11 patients with malignancy and metallic stents were deployed for palliation. In nine of 11 patients with malignant lesions the PTBD dislodgement of the plastic stent and insertion of a metallic stent was carried out as a single-step procedure. In two patients with biliary sepsis, a two-step procedure was necessary. In the patient with Mirizzi's syndrome the plastic stent could not be dislodged. No complications were observed. CONCLUSION: Plastic stents, inserted at ERCP, can be dislodged in the majority of cases at PTBD using a balloon catheter inserted alongside the failed stent without complication.

Value of MR pancreatography in the evaluation of patients with chronic pancreatitis.

AIM: To determine the diagnostic accuracy of magnetic resonance (MR) pancreatography and to define its role in the imaging work-up of patients with severe chronic pancreatitis. MATERIAL AND METHODS: Thirty-two patients (13 men and 19 women; 15-84 years old; mean age, 48 years) with severe chronic pancreatitis diagnosed using cross-sectional imaging, examination using contrast medium (endoscopic retrograde cholangiopancreatography, pseudocyst injection) and/or surgical findings underwent MR pancreatography performed using a two-dimensional multi-slice fast spin echo technique. All patients underwent transabdominal pancreatic sonography and computed tomography (CT) was performed in 12 patients. Two observers independently assessed the MR pancreatograms for pancreatic duct dilatation and pancreatic duct abnormalities. Compared to the final diagnosis, the accuracy of MR pancreatography in revealing complications of chronic pancreatitis was calculated and its role in the radiological work-up of patients with chronic pancreatitis evaluated. RESULTS: When compared to the final diagnosis, MR pancreatography showed the following sensitivity, specificity and diagnostic accuracy: for filling defects in pancreatic duct, 56-78%, 100% and 87-94%, respectively; for strictures, 75-88%, 92-96% and 88-94%, respectively; and for pseudocysts 100%, 100% and 100%, respectively. Filling defects were correctly diagnosed in all patients when MR pancreatography was interpreted in combination with cross-sectional imaging. Contrast pancreatography was required for the complete evaluation of strictures and communication with pseudocysts. CONCLUSION: MR pancreatography is poorly sensitive but specific in revealing pancreatic duct filling defects and strictures. However, when MR pancreatography is interpreted in combination with sonography and CT, it provides sufficient information to plan therapy in the majority of patients.

Assessment of Crohn's disease activity by Doppler sonography of the superior mesenteric artery, clinical evaluation and the Crohn's disease activity index: a prospective study.

AIM: Recent data have shown that superior mesenteric artery (SMA) flow rates are significantly increased in active Crohn's disease, suggesting that SMA flow may be a useful, non-invasive index of disease activity. The aim of this prospective study was to evaluate the use of SMA Doppler sonography as an indicator of Crohn's disease activity and to compare with clinical evaluation and the Crohn's disease activity index (CDAI). MATERIALS AND METHODS: Patients with active Crohn's (n = 19), inactive Crohn's (n = 17) and control subjects (n = 17) were evaluated. Categorization of disease activity was based on a reference standard. CDAI scores were also calculated independently. The SMA flow parameters evaluated were resistive index, pulsatility index, end diastolic velocity, peak systolic velocity, time averaged maximum velocity, cross-sectional area and maximum flow volume. RESULTS: Using a three-group ANOVA for each of peak systolic velocity (PSV) (P = 0.01), end-diastolic velocity (EDV) (P = 0.04), pulsatility index (PI) (P = 0.003), time-averaged maximum velocity (TAMV) (P = 0.05), and maximum flow volume (TAMV.CSA) (P = 0.01), there was a significant effect of group. Using post-hoc tests, only EDV (P = 0.01), TAMV (P = 0.02) and TAMV.CSA (P = 0.003) were significantly different between active and inactive Crohn's disease, though with considerable overlap of values for EDV and TAMV. The mean CDAI scores were significantly different between patients with active Crohn's (287) and inactive Crohn's (71) (P = 0.0001) and correlated well with the reference standard. CONCLUSION: Only three of several parameters previously described as allowing Crohn's disease activity assessment actually did so in our study. However, for two of these parameters (EDV, TAMV), there was overlap between the measurements in the active and inactive groups, thus limiting the ability to discriminate disease activity in practice. The degree of overlap for maximum flow volume (TAMV.CSA) between active and inactive disease was considerably less and this parameter may be more discriminatory of disease activity. On the other hand, we found CDAI scores to be accurate in disease categorization. We agree that there appear to be hyperdynamic changes in active Crohn's disease but suggest that Doppler ultrasound assessment does not reliably assess disease activity in routine clinical practice.

Percutaneous gastrostomy in patients who fail or are unsuitable for endoscopic gastrostomy.

PURPOSE: Percutaneous endoscopic gastrostomy (PEG) is not possible or fails in some patients. We aimed to categorize the reasons for PEG failure, to study the success of percutaneous radiologic gastrostomy (PRG) in these patients, and to highlight the associated technical difficulties and complications. METHODS: Forty-two patients (28 men, 14 women; mean age 60 years, range 18-93 years) in whom PEG failed or was not possible, underwent PRG. PEG failure or unsuitability was due to upper gastrointestinal tract obstruction or other pathology precluding PEG in 15 of the 42 patients, suboptimal transillumination in 22 of 42 patients, and advanced cardiorespiratory decompensation precluding endoscopy in five of 42 patients. T-fastener gastropexy was used in all patients and 14-18 Fr catheters were inserted. RESULTS: PRG was successful in 41 of 42 patients (98%). CT guidance was required in four patients with altered upper gastrointestinal anatomy. PRG failed in one patient despite CT guidance. In the 16 patients with high subcostal stomachs who failed PEG because of inadequate transillumination, intercostal tube placement was required in three and cephalad angulation under the costal margin in six patients. Major complications included inadvertent placement of the tube in the peritoneal cavity. There was one case of hemorrhage at the gastrostomy site requiring transfusion and one case of superficial gastrostomy site infection requiring tube removal. Minor complications included superficial wound infection in six patients, successfully treated with routine wound toilette. CONCLUSION: We conclude that PRG is a safe, well-tolerated and successful method of gastrostomy and gastrojejunostomy insertion in the technically difficult group of patients who have undergone an unsuccessful PEG. In many such cases optimal clinical evaluation will suggest primary referral for PRG as the preferred option.

Diagnostic accuracy of magnetic resonance cholangiopancreatography and ultrasound compared with direct cholangiography in the detection of choledocholithiasis.

AIM: To determine the diagnostic accuracy of magnetic resonance cholangiopancreatography (MRCP) and trans-abdominal ultrasound in the detection of choledocholithiasis, and to compare bile duct stone characteristics using endoscopic retrograde cholangiopancreatography (ERCP), MRCP and ultrasound. MATERIALS AND METHODS: Of 191 consecutive patients referred for diagnostic ERCP, choledocholithiasis was diagnosed in 34 patients using direct cholangiography. The latter took the form of ERCP (n = 29), intraoperative cholangiography (n = 3) or percutaneous transhepatic cholangiography (n = 2). All patients underwent MRCP and ultrasound examinations and their findings for choledocholitiasis were compared with those at direct cholangiography. Finally, in the 29 patients with choledocholithiasis diagnosed under ERCP, stone characteristics were compared across the three investigations of ERCP, MRCP and ultrasound. RESULTS: Compared with direct cholangiography, MRCP showed a sensitivity, specificity and diagnostic accuracy of 91%, 98% and 97%, respectively, in the diagnosis of choledocholithiasis. MRCP resulted in three false-negative and three false-positive findings, four of which occurred due to confusion with lesions at the ampulla. Ultrasound showed a sensitivity, specificity and diagnostic accuracy of 38%, 100% and 89%, respectively, in the diagnosis of choledocholithiasis. ERCP revealed a greater number of stones and these were more proximally distributed within the bile ducts when compared to MRCP. CONCLUSIONS: MRCP is highly accurate in the diagnosis of choloedocholithiasis and has the potential to replace diagnostic ERCP. MRCP underestimates the number of bile duct stones present.

A prospective comparative study of MR sialography and conventional sialography of salivary duct disease.

OBJECTIVE: The purpose of this study was to determine the diagnostic accuracy of MR sialography in the examination of patients with salivary duct disease. SUBJECTS AND METHODS: Forty-nine patients (23 males and 26 females; 16-78 years old; mean age, 47 years) with symptoms related to the salivary glands underwent both conventional sialography and MR sialography. The latter was performed using a heavily T2-weighted, two dimensional, fast spin-echo technique and a 12-cm circular surface coil. Contiguous 3-mm axial images with frequency-selective fat suppression were acquired through the symptomatic gland. The MR sialography findings were compared with the final diagnoses determined by conventional sialography. RESULTS: Conventional sialography showed calculus disease (n = 13), stricture (n = 12), sialectasis (n = 4), cast (n = 3), neoplasm (n = 2), and normal duct (n = 16). MR sialography alone had a sensitivity of 69% in revealing calculus disease. However, the sensitivity increased to 100% when MR sialograms were combined with control radiographs. MR sialography was sufficient to accurately reveal stricture, sialectasis, and neoplasm and to direct therapy on the basis of its findings. Overall, MR sialography combined with control radiographs had a sensitivity, specificity, and diagnostic accuracy of 100%, 88%, and 96%, respectively, in revealing salivary duct abnormalities. CONCLUSION: MR sialography alone is not sufficiently sensitive to reveal salivary duct stones. Caution must be exercised when excluding calculus disease. MR sialography, when combined with control radiographs, is accurate and has the potential to replace conventional sialography.

Role of MR cholangiopancreatography in patients with failed or inadequate ERCP.

OBJECTIVE: The purpose of our study was to evaluate the usefulness of MR cholangiopancreatography in the diagnosis and further treatment of patients with failed or inadequate ERCP. SUBJECTS AND METHODS: Fifty-eight patients with failed or inadequate ERCP underwent MR cholangiopancreatography using a two-dimensional heavily T2-weighted multislice fast spin-echo technique. The final diagnosis was made on the basis of a second ERCP (n = 4), percutaneous transhepatic cholangiopancreatography (n = 19), intraoperative cholangiography (n = 6), percutaneous biopsy (n = 3), surgical findings (n = 5), or clinical follow-up (n = 21) for a mean period of 22 months (range, 7-31 months). RESULTS: MR cholangiopancreatography was technically successful in 57 patients and resulted in a sensitivity, specificity, and diagnostic accuracy of 97.1%, 100%, and 98.2%, respectively. Overall, MR cholangiopancreatography gave clinically useful information that contributed to patient management in 56 (96.6%) of the 58 patients. On the basis of the MR cholangiopancreatography findings, patients were managed using a second ERCP (n = 4), combined percutaneous and endoscopic procedure (n = 2), percutaneous biliary stent insertion (n = 13), surgery (n = 12), chemotherapy (n = 1), or conservative treatment (n = 24). CONCLUSION: MR cholangiopancreatography was found to have a unique and valuable role in the investigation of patients in whom ERCP failed or was inadequate. MR cholangiopancreatography helped us avoid using invasive procedures such as percutaneous transhepatic cholangiography in the diagnosis of bile duct disease after failed ERCP.

Evaluation of dynamic gadolinium-enhanced breath-hold MR angiography in the diagnosis of renal artery stenosis.

OBJECTIVE: The aim of our study was to evaluate a three-dimensional gadolinium-enhanced breath-hold MR angiography sequence using standard MR gradients in detecting renal artery stenosis. SUBJECTS AND METHODS: Forty-two patients referred for angiography for suspected renal artery stenosis underwent both conventional digital subtraction angiography (DSA) and MR angiography. MR angiography was performed on a 1.5-T scanner with standard gradients. A fast multiplanar spoiled gradient-echo sequence was used with the following parameters: TR/TE, 10.3/1.9; flip angle, 45 degrees; field of view, 36 x 32 cm; matrix size, 256 x 128; one excitation; volume thickness, 70 mm; and partitions, 28. Gadolinium was administered IV as a dynamic bolus of 30-40 ml. Conventional and MR angiographic images were interpreted by two radiologists in consensus. RESULTS: DSA revealed 87 renal arteries, of which 79 were in 35 patients with native kidneys and eight arteries were in seven patients with transplanted kidneys. Gadolinium-enhanced MR angiography showed 85 (98%) of 87 renal arteries. Seventeen patients had 20 significant (>50% stenosis) renal artery stenoses and five patients had five occluded renal arteries revealed by DSA. MR angiography revealed 85 renal arteries (98%), 20 stenoses (100%), and five occlusions (100%). Gadolinium-enhanced MR angiography led to one false-positive interpretation for renal artery stenosis and no false-negative interpretations. Thus, the sensitivity, specificity, and accuracy of MR angiography for renal artery stenosis were 100%, 98%, and 99%, respectively. CONCLUSION: The MR angiography pulse sequence we used was an effective and reliable technique for the diagnosis of renal artery stenosis. The sequence can be performed on widely available MR equipment that does not require fast gradient hardware.

The diagnostic accuracy of magnetic resonance cholangiopancreatography and ultrasound compared with direct cholangiography in the detection of choledocholithiasis.

AIM: To determine the diagnostic accuracy of magnetic resonance cholangiopancreatography (MRCP) and ultrasound (US) in the diagnosis of choledocholithiasis in a large group of patients with bile duct stones confirmed at direct cholangiography. Also, to compare bile duct stones confirmed at direct cholangiography. Also, to compare bile duct stone characteristics using the three different investigations, endoscopic retrograde cholangiopancreatography (ERCP), MRCP and US. MATERIALS AND METHODS: 191 patients (M:F, 76:115; mean age, 66 years; range, 24-92 years) were investigated by direct cholangiography, MRCP and US. Their final diagnosis as determined at direct cholangiography were choledocholithiasis (n = 34), strictures (n = 47) and normal ducts (n = 110). The direct cholangiographic methods used for diagnosis of choledocholithiasis were ERCP (n = 29), intraoperative cholangiography (n = 3) and percutaneous transhepatic cholangiography (n = 2). The bile duct stone characteristics were compared using ERCP, MRCP and US in the 29 patients in whom stones were exclusively diagnosed by ERCP. RESULTS: Compared with the final diagnosis, MRCP had a sensitivity, specificity and diagnostic accuracy of 91%, 98% and 97%, respectively, in the diagnosis of choledocholithiasis. MRCP resulted in three false-negative and three false-positive findings, four of which occurred due to confusion with lesions at the ampulla. US had a sensitivity, specificity and diagnostic accuracy of 38%, 100% and 89%, respectively, in the diagnosis of choledocholithiasis. ERCP diagnosed more stones and the stones were more proximally distributed within the bile duct at ERCP when compared with MRCP. CONCLUSION: MRCP has a high diagnostic accuracy (97%), similar to that at direct cholangiography, in the diagnosis of choloedocholithiasis. It has the potential to replace diagnostic ERCP and select patients with choledocholithiasis for therapeutic ERCP.

A three-dimensional gadolinium-enhanced MR venography technique for imaging central veins.

OBJECTIVE: We evaluated the use of a three-dimensional gadolinium-enhanced MR venography technique in selected patients with suspected central venous abnormalities. SUBJECTS AND METHODS: Thirty-seven patients with suspected thrombosis, stenosis, occlusion, or compression of the axillary vein, subclavian vein, brachiocephalic vein, or superior or inferior vena cava or with suspected malfunction of central venous catheters were imaged. For all patients, we obtained a three-dimensional dynamic gadolinium-enhanced (bolus injection, 30 40 ml) breath-hold spoiled gradient-recalled acquisition in the steady state as well as conventional venous images from either Doppler sonography, CT, or digital subtraction venography. Breathhold fast multiplanar spoiled gradient-recalled acquisitions in the steady state were obtained using the following parameters: TR/TE, 10.3/1.9; flip angle, 45 degrees; matrix size, 256 x 128; number of excitations, one; field of view, 36-48 cm; number of partitions, 28; and slice thickness, 2.54 mm. MR venograms and conventional images were interpreted by two observers in consensus who were unaware of clinical information and the diagnosis. RESULTS: MR venograms were of diagnostic quality for all 37 patients. Thirteen patients had normal venous systems seen on both conventional and MR images. MR venography showed all nine venous stenoses, the one pericatheter fibrin sheath, and the one jugular vein thrombosis. Axillary or subclavian vein thrombosis was correctly diagnosed with MR venography in all four patients with this condition. Mediastinal venous compression was accurately depicted by MR venography in the five patients who had such compression. Finally, MR venography revealed the correct diagnosis in the three patients with inferior vena cava thrombus and tumor and the one patient with inferior vena cava compression. Thus, MR venography was 100% sensitive, specific, and accurate in the diagnosis of abnormalities affecting large central veins. CONCLUSION: Compared with conventional imaging, gadolinium-enhanced breathhold MR venography is easy to perform, well tolerated, and highly accurate in depicting central venous abnormalities.

Routine chest radiographs after central line insertion: mandatory postprocedural evaluation or unnecessary waste of resources?

PURPOSE: To study the cost and impact on patient management of the routine performance of chest radiographs in patients undergoing imaged-guided central venous catheter insertion. METHODS: Six hundred and twenty-one catheters placed in 489 patients over a 42-month period formed the study group. Catheters were placed in the right internal jugular vein (425), left internal jugular vein (133), and subclavian veins (63). At the end of the procedure fluoroscopy was used to assess catheter position and check for complications. A postprocedural chest radiograph was obtained in all patients. RESULTS: Postprocedural chest fluoroscopy showed no evidence of pneumothorax, hemothorax, or mediastinal hematoma. Inappropriate catheter tip position or catheter kinks were noted with 90 catheters. These problems were all corrected while the patient was on the interventional table. Postprocedural chest radiographs showed no complications but proximal catheter tip migration was noted in six of 621 catheters (1%). These latter six catheters required further manipulation. The total technical and related charges for the postprocedural chest radiographs in this series were estimated at pound15,525. CONCLUSION: Postprocedural chest radiographs after image-guided central venous catheter insertion are not routinely required. A postprocedural chest radiograph can be performed on a case-by-case basis at the discretion of the interventional radiologist.

A prospective comparison of magnetic resonance cholangiopancreatography with endoscopic retrograde cholangiopancreatography in the evaluation of patients with suspected biliary tract disease.

AIM: To determine the diagnostic accuracy of magnetic resonance cholangiopancreatography (MRCP) compared with direct cholangiography in the detection of biliary tract disease. PATIENTS AND METHODS: MRCP was performed in 100 patients in whom direct cholangiographic correlation (ERCP, n = 98; PTC, n = 9; intraoperative cholangiography, n = 3) was available for comparison. The MRCP examinations were performed using a two-dimensional multi-slice, fast spin echo (FSE) technique and a local surface coil. The diagnoses at direct cholangiography were choledocholithiasis in 30 patients, benign and malignant strictures in 28 patients and normal bile ducts in 42 patients. The nature of the strictures (benign, n = 2; tumour, n = 18; lymphnode recurrence, n = 3; unknown histology, n = 5) was determined by one or more of the following procedures: surgery (n = 8), biopsy (n = 15), cytology (n = 6) and cross-sectional imaging/follow-up findings (n = 3). RESULTS: MRCP diagnosed choledocholithiasis with a sensitivity of 93%, specificity of 99% and accuracy of 97 %. It resulted in two false-negative and one false-positive findings when compared with direct cholangiography. MRCP accurately diagnosed the presence and level of strictures in all patients. The overall sensitivity, specificity and accuracy of MRCP in the detection of bile duct lesions were 97%, 98% and 97%, respectively. CONCLUSION: MRCP has a high diagnostic accuracy when compared with direct cholangiography in the detection of bile duct disease.

Evaluation of the role of magnetic resonance myelography in lumbar spine imaging.

The purpose of our study was to evaluate the accuracy of MR myelography in depicting disc herniation in the lumbar spine when compared with conventional MRI in patients presenting with clinical evidence of disc herniation. One hundred patients referred for conventional MR imaging of the lumbar spine also had coronal MR (TR 9000 ms, TE 272 ms eff, NEX 3, echo train length 32) myelography performed. Three experienced observers compared magnetic resonance myelography (MRM) with conventional lumbar spine MR using the following variables: visibility of thecal sac and nerve roots, and the presence, location and severity of disc herniation. Disc protrusions were seen at 110 disc space levels on conventional MR images as opposed to 93 on MRM. However, only 72 % of lesions seen on conventional MR were diagnosed by MRM. Similarly, only 63.8 % of nerve root compression abnormalities seen at conventional MR were visualized when compared with conventional MRM. The sensitivity, specificity and accuracy of MRM when compared with conventional MR was 72, 93 and 85 %, respectively. The MRM technique yields images that resemble conventional myelography and may be used to help confirm abnormalities seen on conventional MR in selected cases; however, the large number of false-positive and false-negative examinations indicates that caution should be used in interpreting MRM images.

Comparison of digital subtraction angiography with gadolinium-enhanced magnetic resonance angiography in the diagnosis of renal artery stenosis.

Renal artery stenosis (RAS) is a treatable cause of hypertension and renal failure for which no ideal screening technique is currently available. We evaluated the use of dynamic gadolinium-enhanced magnetic resonance angiography (MRA) for the diagnosis of RAS. Sixty-two patients with secondary hypertension were enrolled in the study. All patients had conventional renal angiography and gadolinium enhanced MRA. The sequence used was a 3D FMP SPGR sequence with the following parameters (TR: 26 ms, TE: 6.9 ms, flip angle 40 degrees, field of view 36 x 36 cm, matrix 246 x 256, 1 excitation). Gadolinium 0.3 mmol/kg was administered and 60 1. 5-mm-thick partitions were obtained over a duration of 3.5 min. The MRA images were then compared with conventional digital subtraction angiography (DSA) images. Conventional DSA demonstrated 138 renal arteries, whereas gadolinium-enhanced MRA demonstrated 129 (93 %). Twenty-one renal artery stenoses and four occluded arteries were seen at conventional DSA. Gadolinium-enhanced MRA had a sensitivity of 88 %, specificity of 98 %, accuracy of 96 %, positive predictive value of 92 % and negative predictive value of 97 % when compared with conventional DSA. Gadolinium-enhanced MRA is an accurate technique for identifying patients with RAS. It is less sensitive in picking up accessory renal arteries.

MR differentiation of phaeochromocytoma from other adrenal lesions based on qualitative analysis of T2 relaxation times.

AIM: To determine the diagnostic accuracy of MR imaging in differentiating phaeochromocytoma from other adrenal lesions. MATERIALS AND METHODS: Sixty-seven adrenal masses (65 patients) including 17 phaeochromocytomas were imaged using T2-weighted pulse sequences on 0.6 T and 1.5 T GE MR units. The adrenal lesions were qualitatively assessed by three observers and divided into three categories (benign adenomas, malignant lesions and phaeochromocytomas) based on lesion signal intensity relative to liver and cerebrospinal fluid. RESULTS: Eleven phaeochromocytomas (65%) were correctly identified while the remaining six (35%) were misclassified, five as malignant lesions and one as a benign adenoma, because of atypical low signal intensity on T2-weighted MR images. Conversely, six non-phaeochromocytomas (three benign adenomas, two adrenal carcinomas and one metastasis) were wrongly classified as phaeochromocytomas because of very high lesion signal intensity. The sensitivity of MR imaging for diagnosing phaeochromocytoma was 64.7%, specificity 88.0%, positive predictive value 64.7% and negative predictive value 88.0%. CONCLUSION: There is considerable overlap between the MR appearance of phaeochromocytoma and other adrenal lesions. A phaeochromocytoma cannot be excluded on the basis of a lack of high signal intensity on T2-weighted MR imaging.